IMPROVEMENT OF SELECTIVITY WITH NUMERICAL DERIVATIVE TECHNIQUES IN INDUCTIVELY COUPLED PLASMA ATOMIC EMISSION-SPECTROMETRY

One of the most attractive features of derivative spectrometry is its higher resolving power. In the present power, numerical derivative techniques are evaluated from the viewpoint of increase in selectivity, the latter being expressed in terms of the interferent equivalent concentration (IEC). Typical spectral interferences are covered, including flat background, sloped background, simple curved background and various types of line overlap with different overlapping degrees, which were defined as the ratio of the net interfering signal at the analysis wavelength to the peak signal of the interfering line. the IECs in the derivative spectra are decreased by one to two order of magnitudes compared to those in the original spectra, and in the most cases, assume values below the conventional detection limits. The overlapping degree is the dominant factor that determines whether an analysis line can be resolved from an interfering line with the derivative techniques. Generally, the second derivative technique is effective only for line overlap with an overlapping degree of less than 0.8. The effects of other factors such as line shape, data smoothing, step size and the intensity ratio of analyte to interferent on the performance of the derivative techniques are also discussed. All results are illustrated with practical examples.

基于加速度反馈的柔性关节机械臂接触力控制

针对柔性关节机械臂从自由空间运动控制过渡到约束空间力控制的过程中,存在冲击、震荡甚至不稳定等问题,利用加速度传感器反馈控制,为柔性关节机械臂的接触力控制在较宽的带宽内提供阻尼,克服了利用单纯速度反馈控制带宽窄的局限。对柔性关节机械臂的接触力控制进行建模和基于加速度反馈的控制策略分析,并在柔性关节机械臂上进行了接触力控制的试验研究。结果表明,这种方法有效。

基于加速度传感器反馈控制的谐波驱动系统的研究

在机器人驱动中经常采用谐波传动。但谐波减速器的柔性、非线性摩擦、随速度波动、低阻尼等因素会给负载端带来振动 ,导致工作端的轨迹跟踪精度不高。为了抑制其振动 ,实现高精度轨迹跟踪控制 ,提出利用加速度传感器反馈控制来抑制负载端的振动、力矩干扰和动力学效应 ,提高其响应性能。理论分析和实验结果证实了提出方法的可行性。

基于CAN总线的分布式数据采集与控制系统

随着电子技术和计算机技术的不断发展，工业生产过程的控制系统正在向着智能化、数字化和网络化的方向发展。传统的集散控制方式和计算机分层控制方式已经开始让位于智能终端与网络结合的总线网络控制方式。当今，在工厂中过程控制环境下的分布式自动化系统变得越来越复杂，尤其系统内部的各设备之间需要快速交换大量的信息，以便实现对被控系统更为精确的控制和提供一些辅助的评价函数。这就意味着要不断增加带宽和提高通信速率以满足网络通信的需要。在现有的多种可利用网络设备中，CAN总线以其清晰的定义、极高的可靠性及其独特的设计，被认为是最能有效地解决这一问题的途径之一。而且市场上基于通信技术的产品中，就实时性考虑，由于CAN总线采用的非表意性的通信方式，因此其结构更为简单，实时性更好。基于此背景，我们以CAN总线作为通信媒介，将分布于各控制现场的传感器、执行器和控制器有序地连接起来，构成了一个基于CAN总线的分布式局域网络控制系统。本文首先介绍了基于CAN总线的分布式数据采集与控制系统的总体结构。然后从硬件方面描述了基于CAN总线的通信协议转换单元、数据采集单元和输出控制单元的功能、硬件配置及各单元功能的具体实现过程，给出了各单元的性能指标。软件方面，以C语言作为平台，开发了基于CAN总线的上位计算机管理与监控软件，实现了对整个网络设备的系统管理和系统控制功能。对于该总线系统，作者运用了PID控制和模糊控制算法实现了对水箱液位的控制，达到了理想的效果。基于CAN总线的控制系统很好地解决了集散控制系统难以解决的难题，模糊控制的应用能很好地把总线控制系统应用到具有非线性、大时滞和难于获得精确模型的控制系统中。

叠前地震数据规则化、重建及噪音压制

I address of reconstruction of spatial irregular sampling seismic data to regular grids. Spatial irregular sampling data impairs results of prestack migration, multiple attenuations, spectra estimation. Prestack 5-D volumes are often divided into sub-sections for further processing. Shot gathers are easy to obtain from irregular sampling volumes. My strategy for reconstruction is as follows: I resort irregular sampling gathers into a form of easy to bin and perform bin regularization, then utilize F-K inversion to reconstruct seismic data. In consideration of poor ability of F-K regularization to fill in large gaps, I sort regular sampling gathers to CMP and proposed high-resolution parabolic Radon transform to interpolate data and extrapolate offsets. To strong interfering noise--multiples, I use hybrid-domain high-resolution parabolic Radon transform to attenuate it. F-K regularization demand ultimately for lower computing costs. I proposed several methods to further improve efficiency of F-K inversion: first I introduce 1D and 2D NFFT algorithm for a rapid calculation of DFT operators; then develop fast 1D and 2D CG method to solve least-square equations, and utilize preconditioner to accelerate convergence of CG iterations; what’s more, I use Delaunay triangulation for weight calculation and use bandlimit frequency and varying bandwidth technique for competitive computation. Numerical 2D and 3D examples are offered to verify reasonable results and more efficiency. F-K regularization has poor ability to fill in large gaps, so I rearrange data as CMP gathers and develop hybrid-domain high-resolution parabolic Radon transforms which be used ether to interpolate null traces and extrapolate near and far offsets or suppress a strong interfere noise: multiples. I use it to attenuate multiples to verify performances of our algorithm and proposed routines for industrial application. Numerical examples and field data examples show a nice performance of our method.

基于匹配追踪方法的地震信号时频分析研究

Seismic signal is a typical non-stationary signal, whose frequency is continuously changing with time and is determined by the bandwidth of seismic source and the absorption characteristic of the media underground. The most interesting target of seismic signal’s processing and explaining is to know about the local frequency’s abrupt changing with the time, since this kind of abrupt changing is indicating the changing of the physical attributes of the media underground. As to the seismic signal’s instantaneous attributes taken from time-frequency domain, the key target is to search a effective, non-negative and fast algorithm time-frequency distribution, and transform the seismic signal into this time-frequency domain to get its instantaneous power spectrum density, and then use the process of weighted adding and average etc. to get the instantaneous attributes of seismic signal. Time-frequency analysis as a powerful tool to deal with time variant non-stationary signal is becoming a hot researching spot of modern signal processing, and also is an important method to make seismic signal’s attributes analysis. This kind of method provides joint distribution message about time domain and frequency domain, and it clearly plots the correlation of signal’s frequency changing with the time. The spectrum decomposition technique makes seismic signal’s resolving rate reach its theoretical level, and by the method of all frequency scanning and imaging the three dimensional seismic data in frequency domain, it improves and promotes the resolving abilities of seismic signal vs. geological abnormal objects. Matching pursuits method is an important way to realize signal’s self-adaptive decomposition. Its main thought is that any signal can be expressed by a series of time-frequency atoms’ linear composition. By decomposition the signal within an over completed library, the time-frequency atoms which stand for the signal itself are selected neatly and self-adaptively according to the signal’s characteristics. This method has excellent sparse decomposition characteristics, and is widely used in signal de-noising, signal coding and pattern recognizing processing and is also adaptive to seismic signal’s decomposition and attributes analysis. This paper takes matching pursuits method as the key research object. As introducing the principle and implementation techniques of matching pursuits method systematically, it researches deeply the pivotal problems of atom type’s selection, the atom dictionary’s discrete, and the most matching atom’s searching algorithm, and at the same time, applying this matching pursuits method into seismic signal’s processing by picking-up correlative instantaneous messages from time-frequency analysis and spectrum decomposition to the seismic signal. Based on the research of the theory and its correlative model examination of the adaptively signal decomposition with matching pursuit method, this paper proposes a fast optimal matching time-frequency atom’s searching algorithm aimed at seismic signal’s decomposition by frequency-dominated pursuit method and this makes the MP method pertinence to seismic signal’s processing. Upon the research of optimal Gabor atom’s fast searching and matching algorithm, this paper proposes global optimal searching method using Simulated Annealing Algorithm, Genetic Algorithm and composed Simulated Annealing and Genetic Algorithm, so as to provide another way to implement fast matching pursuit method. At the same time, aimed at the characteristics of seismic signal, this paper proposes a fast matching atom’s searching algorithm by means of designating the max energy points of complex seismic signal, searching for the most optimal atom in the neighbor area of these points according to its instantaneous frequency and instantaneous phase, and this promotes the calculating efficiency of seismic signal’s matching pursuit algorithm. According to these methods proposed above, this paper implements them by programmed calculation, compares them with some open algorithm and proves this paper’s conclusions. It also testifies the active results of various methods by the processing of actual signals. The problems need to be solved further and the aftertime researching targets are as follows: continuously seeking for more efficient fast matching pursuit algorithm and expanding its application range, and also study the actual usage of matching pursuit method.

基于精细结构描述及数值试验的断续节理岩体力学参数智能选取

Evaluating the mechanical properties of rock masses is the base of rock engineering design and construction. It has great influence on the safety and cost of rock project. The recognition is inevitable consequence of new engineering activities in rock, including high-rise building, super bridge, complex underground installations, hydraulic project and etc. During the constructions, lots of engineering accidents happened, which bring great damage to people. According to the investigation, many failures are due to choosing improper mechanical properties. ‘Can’t give the proper properties’ becomes one of big problems for theoretic analysis and numerical simulation. Selecting the properties reasonably and effectively is very significant for the planning, design and construction of rock engineering works. A multiple method based on site investigation, theoretic analysis, model test, numerical test and back analysis by artificial neural network is conducted to determine and optimize the mechanical properties for engineering design. The following outcomes are obtained: (1) Mapping of the rock mass structure Detailed geological investigation is the soul of the fine structure description. Based on statistical window，geological sketch and digital photography，a new method for rock mass fine structure in-situ mapping is developed. It has already been taken into practice and received good comments in Baihetan Hydropower Station. (2) Theoretic analysis of rock mass containing intermittent joints The shear strength mechanisms of joint and rock bridge are analyzed respectively. And the multiple modes of failure on different stress condition are summarized and supplied. Then, through introducing deformation compatibility equation in normal direction, the direct shear strength formulation and compression shear strength formulation for coplanar intermittent joints, as well as compression shear strength formulation for ladderlike intermittent joints are deducted respectively. In order to apply the deducted formulation conveniently in the real projects, a relationship between these formulations and Mohr-Coulomb hypothesis is built up. (3) Model test of rock mass containing intermittent joints Model tests are adopted to study the mechanical mechanism of joints to rock masses. The failure modes of rock mass containing intermittent joints are summarized from the model test. Six typical failure modes are found in the test, and brittle failures are the main failure mode. The evolvement processes of shear stress, shear displacement, normal stress and normal displacement are monitored by using rigid servo test machine. And the deformation and failure character during the loading process is analyzed. According to the model test, the failure modes quite depend on the joint distribution, connectivity and stress states. According to the contrastive analysis of complete stress strain curve, different failure developing stages are found in the intact rock, across jointed rock mass and intermittent jointed rock mass. There are four typical stages in the stress strain curve of intact rock, namely shear contraction stage, linear elastic stage, failure stage and residual strength stage. There are three typical stages in the across jointed rock mass, namely linear elastic stage, transition zone and sliding failure stage. Correspondingly, five typical stages are found in the intermittent jointed rock mass, namely linear elastic stage, sliding of joint, steady growth of post-crack, joint coalescence failure, and residual strength. According to strength analysis, the failure envelopes of intact rock and across jointed rock mass are the upper bound and lower bound separately. The strength of intermittent jointed rock mass can be evaluated by reducing the bandwidth of the failure envelope with geo-mechanics analysis. (4) Numerical test of rock mass Two sets of methods, i.e. the distinct element method (DEC) based on in-situ geology mapping and the realistic failure process analysis (RFPA) based on high-definition digital imaging, are developed and introduced. The operation process and analysis results are demonstrated detailedly from the research on parameters of rock mass based on numerical test in the Jinping First Stage Hydropower Station and Baihetan Hydropower Station. By comparison，the advantages and disadvantages are discussed. Then the applicable fields are figured out respectively. (5) Intelligent evaluation based on artificial neural network (ANN) The characters of both ANN and parameter evaluation of rock mass are discussed and summarized. According to the investigations, ANN has a bright application future in the field of parameter evaluation of rock mass. Intelligent evaluation of mechanical parameters in the Jinping First Stage Hydropower Station is taken as an example to demonstrate the analysis process. The problems in five aspects, i. e. sample selection, network design, initial value selection, learning rate and expected error, are discussed detailedly.

尺度匹配方法在井震联合重建和多次波衰减中的应用

Scale matching method means adjusting information with different scale to the same level. This thesis focuses on scale unification of information with different frequency bandwidth. Well-seismic cooperate inversion is an important component of reservoir geophysics; multiple prediction & subtraction is a development of multiple attenuation in recent years. The common ground of these two methods is that they both related to different frequency bandwidth unification. Well log、cross-hole seismic、VSP、3D seismic and geological information have different spatial resolution, we can decrease multi-solution of reservoir inversion and enhance the vertical and lateral resolution of the geological object by integrate those information together; Compare the predicted multiple generated by SRME with the real multiple, we find the predicted multiple convolutes at least one wavelet more, which brings frequency bandwidth difference between them. So the subtraction method also relates to multi-scale information unification. This thesis gives a method of well constrained seismic high resolution processing basing on auto gain control modulation. It uses base function method which utilizes original well-seismic match result as initial condition and processed seismic trace as initial model to extrapolate the high frequency information of the well logs to the seismic profiles. In this way we can broaden the bandwidth of the seismic and make the high frequency gain geological meaning. In this thesis we introduce the revised base function method to adaptive subtraction and verify the validity of the method using models. Key words: high frequency reconstruction, scale matching, base function, multiple, SRME prediction & subtraction

地震采集观测系统的共聚焦分析

Focal beam analysis is a method for assessment of acquisition geometries that is directly linked to pre-stack migration. About dealing with the complex subsurface structures, the conventional survey design methods which do not take into account the subsurface are no longer valid. Based on the Fourier finite-difference (FFD) large-step wave field extrapolation and Born-Kirchhoff (BK) small-step wavefield interpolation, the thesis presents a rapid resolution analysis of 3D seismic survey design by focal beams in complicated media. Subsequently, The SEG/EAEG salt model is used to illustrate the method. Based on the focal beam resolution definition, each kind of influence factor is discussed. The focal beam analysis usually is carried out in a single frequency, but the actual seismic waves always contain a frequency bandwidth. In this thesis, theoretical relationship between focal beam analysis and frequency is derived. Since the effects of focal beam analysis are linear with frequency simply, the multi-frequency focal beam analysis using interpolation is developed. At the same time, the resolution of different frequency bandwidth is interconvertible in accordance with Signal uncertainty principle. The resolution of all frequency bands can be calculated by using only a few focal beam analysis for a seismic survey. In the last section of this thesis, I propose a new approach to predicting acquisition footprint, based on the assumption of Common-Middle-Point stack without constructing a special velocity model. The approach is a simplistic analytical method in which the acquisition footprint pattern is a weighted, linear summation of limited-offset fold-of-stack plots. Because the value of acquisition can be got by quantificational and rapidly calculating, we can exactly do a comparative analysis among different plans of seismic survey by this method.